Centrifuge discharge means



Sept. 24, 1963 w. A. some CENTRIFUGE DISCHARGE MEANS I Filed Jan. 4,1962 ATTORNEY United States Patent 3,105,045 CENTRIFUGE DISCHARGE MEANSWalter A. Borig, Wayne, Pa, assignor to The Sharples Corporation, acorporation of Delaware Filed Jan. 4, 1962, Ser. No. 163,995 2 Claims.(Cl. 23322) This invention relates to the separation of solids fromliquid. More specifically this invention relates to an apparatus forseparating solids from liquids by centrifugal force and provides meansfor facilitating the discharge of the solids.

In the prior art, apparatus for separating solids from liquid hascomprised an imperforate rotor and a screw within the rotor operativelyconnected to the rotor for relative movement between the rotor and thescrew upon rotation of the rotor. Liquid and solids discharge openingshave been provided at opposite ends of the rotor and means havedelivered feed into the rotor at a point intermediate the ends. Inoperation, the solids in the feed have, under centrifugal force, beenthrown against the wall of the rotor and the screw, moving relatively tothe rotor, has plowed the solids toward the solids opening fordischarge. The liquid, separated from the solids, has discharged throughthe liquid opening.

Apparatuses of the general type with which the present invention isconcerned are disclosed, for instance, in US. Patent 2,703,676, issuedMarch 8, 1955, on application filed by F. P. Gooch, and also US. Patent3,061,181, issued October 30, 1962, on an application filed by F. P.Gooch.

In such prior art devices difliculty has occasionally been experiencedby the tendency of some solids discharging from the rotor to cling tothe inside surfaces of the surrounding casing and to build up thereoninwardly to the rotor. This action has been especially manifest withdischarged solids having a higher liquid content. Such accumulation hasserious consequences: further discharge of solids from the bowl isimpeded; and the interference of accumulated solids with the rotorrequires greater power to rotate the rotor and leads to a condition ofaxial imbalance in suspended rotors, resulting in severe vibrations.

"in the past, attempts have been made to facilitate solids discharge. Arigid metal fabricated shield has been mounted to surround the rotorinside the casing in the zone of solids discharge. Special mounting ofthe shield has enabled the shield to be vibrated by either an electricor air-operated vibrator disposed outside the centrifuge casing. Whileto some extent the powered shield has prevented the accumulation ofsticky wet solids inwardly toward the rotor, it has obviously involvedundesirable expense, has been subject to break-down and has requiredmaintenance. More importantly, when a centrifuge is used in a processrequiring pressure operation, penetration of the centrifuge casing forthe shield driving arm is obviously undesirable.

I have developed an extremely simple yet effective means for eliminatingsolids accumulation in the solids discharge zone. My means isinexpensive, is self-actuating, is not subject to break-downs, andrequires no maintenance.

Other features of my invention will be apparent from the followingspecification of which the accompanying drawings form a part.

In the drawings,

FIGURE 1 is a perspective partly in section of an apparatus embodying myinvention; and

FIGURE 2 is an enlarged fragmentary sectional View taken on the line2--2 of FIGURE 1.

Briefly, in a centrifuge comprising a rotor having at ice least onesolids discharge opening, my invention is the improvement of a curtainof smooth flexible sheet material at least partially circumposing therotor in the zone radially outward from the discharge opening and therebeing free for limited lateral movement. The curtain, vibrated by impactof solids discharge, and by centrifuge windage precludes adherence andinward accumulation of solids. Additionally, the smooth surface of thesheet material contributes in large measure to the effectiveness of theimprovement.

Referring more specifically to the drawings, an apparatus embodying theinvention is generally designated 10 in FIGURE 1. It comprises a casing12 which mounts for rotation about a vertical axis a rotor 14. Drivemeans (not shown) rotate the rotor from its upper end and comprise, forinstance, belts disposed under the guard 16. The rotor 14 contains ascrew 18 to which it is operatively connected for relative movement asdisclosed, for instance, in the latter above-mentioned patentapplication. A drag 243 is supported from the casing 12 on radial arms22 for the purpose of limiting axial aberrations of the lower end of therotor. A feed tube 24 from an appropriate source penetrates the casing12 and extends through the drag 24) for the purpose of delivering feedmixture into the rotor as is well known in the art.

In the operation of the apparatus, feed mixture is conveyed, e.g. as bypump, through the feed tube 24- and into the rotor 14 at a centrallocation, for instance. The rotor in rotating causes the solids ofhigher density than the liquid to move outward to the wall, and thescrew, the flight edges of which are proximate to the wall, plows thesolids to the discharge openings 26 from which they are thrownoutwardly. The liquid discharge means is not shown.

The portion of the apparatus which embodies my invention is shown inFIGURE 1 to comprise a continuous sheet 28 of thin material circumposingthe rotor and spaced intermediate the casing and the rotor. As shown inFIGURE 2 the mounting for the sheet 28 comprises an inward flange 3t)secured about the casing at a level well above the openings 26. Theflange 3t} secures an annular plate 32 which in turn supports a bracket34 comprising an outer clamping ring 34a. An inner clampin ring 36 isprovided and rings 34a, 36 sandwich between them the upper end of thesheet 28 and, along with the sheet, are suitably apertured to receive aplurality of circumferentially spaced mounting bolts 38.

From the upper mounting assembly the sheet 28 comprising the curtain isfreely suspended in the embodiment shown and extends to a level wellbelow the discharge openin s 26. The lower end of the sheet 28 issandwiched by a pair of lower clamping rings 49, 42. The rings, togetherwith the sheet, are suitably apertured to receive oir-cumferentiallyspaced clamping bolts 44, the outer ends of which extend outward fromthe rings 49, 42 to comprise stop elements for the purpose of limitingthe lateral travel or" the lower end of the curtain, to keep it undercontrol. The rings 40, 4-2 provide weight suflicient to hold down thelower end of the curtain but not suflicient to prevent movement of thecurtain by impact of the solids and by the air currents about the rotor.The rings 40, 42 also serve to hold the lower end of the curtain inshape.

As shown in FIGURE 1 ample openings 45 are pro vided in the sheet 28 topermit penetration by the radial arms 22 and the feed tube 24.

The preferred material for sheet '28 is Teflon. Teflon is a Du Ponttrademark for polytetrafiuoroethylene. Thickness of about inch has beenfound suitable. Other materials, having smooth surfaces and considerableflexibility are eliective to some extent and may be used.

In operation, the solids thrown outward from openings 26 impact againstthe sheet or curtain 28 causing it to vibrate. This vibration, enhancedby air currents about the rotor and controlled in amplitude by thelength of the stop elements 44, serves to preclude adherence of thesolids to the sheet 28. Assisting greatly in precluding adherence may bethe smooth and slippery character especially of the preferred materialof the sheet 28.

It should be understood that While the rotor disclosed has its lower endof generally conical shape, the invention may be applied to a rotor ofcylindrical shape if desired.

The lower end of the curtain may be loosely connected to the casing ifdesired, provided such mounting does not interfere with the freedom forlateral movement of the curtain in the zone of solids discharge. -Itshould be understood, however, that the embodiment shown has been foundespecially cfiective.

While the curtain is most eifectively applied to a rotor having avertical axis, it may be used with some benefit on a rotor having ahorizontal axis by supporting the curtain at both ends and by modifyingthe curtain to provide openings for solids discharge through a portionthereof disposed below the axis. However, application to a verticalmachine is preferred.

It is, therefore, to be understood that the above description is by wayof illustration and that changes, omissions, additions, substitutionsa-ncl/ or other modifications may be made without departing from thespirit thereof. Accordingly, it is intended that the patent shall cover,by suitable expression in the claims the various features of patentablenovelty that reside in the invention.

I claim:

1. In a centrifuge comprising a rotor having a vertical axis and havingat least one solids discharge opening, and a stationary casing enclosingsaid rotor, the improvement 4 of a curtain of smooth flexible sheetmaterial circumposing the rotor and spaced inward from the casing at thelevel of the solids discharge opening and therebelow, a pair of clampingrings circumposing the rotor and secured to the casing at a level abovethe solids discharge opening, the top of the curtain being clampedbetween the clamping rings, the curtain hanging downward therefrom, thelower end of the curtain having rigid annular weight means securedthereabou-t, the weight means having a plurality of peripherally spacedradially outstanding stop elements to engage the casing and thereby tolimit the lateral movement of the lower end of the curtain, the curtainbeing free for lateral movement in all radial directions in the zoneoutward from the solidsdischarge opening whereby solids in discharginghit the curtain and vibrate it to preclude solids buildup thereon.

2. A centrifuge as described in claim 1 wherein the flexible sheetmaterial is Teflon.

References Cited in the file of this patent UNITED STATES PATENTS631,680 Staahlgren Aug. 22, 1899 735,524 Kessler Aug. 4, 1903 2,045,986Gould -5 June 30, 1936 2,186,836 McGlaughlin Jan. 9, 1940 2,272,175Jordan Feb. 10, 1942 2,324,933 Jones July 26, 1943 2,367,961 PiponiusIan. 23, 1945 2,661,150 Abbott Dec. 1, 1953 2,703,676 Gooch Mar. 8, 19553,014,642 Lundberg Dec. 26, 1961 3,053,762 Adiletta Sept.'11, 19623,061,181 Gooch Oct. 30, 1962

1. IN A CENTRIFUGE COMPRISING A ROTOR HAVING A VERTICAL AXIS AND HAVINGAT LEAST ONE SOLIDS DISCHARGE OPENING, AND A STATIONARY CASING ENCLOSINGSAID ROTOR, THE IMPROVEMENT OF A CURTAIN OF SMOOTH FLEXIBLE SHEETMATERIAL CIRCUMPOSING THE ROTOR AND SPACED INWARD FROM THE CASING AT THELEVEL OF THE SOLIDS DISCHARGE OPENING AND THEREBELOW, A PAIR OF CLAMPINGRINGS CIRCUMPOSING THE ROTOR AND SECURED TO THE CASING AT A LEVEL ABOVETHE SOLIDS DISCHARGE OPENING, THE TOP OF THE CURTAIN BEING CLAMPEDBETWEEN THE CLAMPING RINGS, THE CURTAIN HANGING DOWNWARD THEREFROM, THELOWER END OF THE CURTAIN HAVING RIGID ANNULAR WEIGHT MEANS SECUREDTHEREABOUT, THE WEIGHT MEANS HAVING A PLURALITY OF PERIPHERALLY SPACEDRADIALLY OUTSTANDING STOP ELEMENTS TO ENGAGE THE CASING AND THEREBY TOLIMIT THE LATERAL MOVEMENT OF THE LOWER END OF THE CURTAIN, THE CURTAINBEING FREE FOR LATERAL MOVEMENT IN ALL RADIAL DIRECTIONS IN THE